The present invention relates to a camera, and relates, more particularly, to a camera using a film cartridge equipped with a light-shielding door to be electrically opened and closed, for example, at a film inlet and outlet opening.
A film cartridge of a film feed-out type currently available in the market is provided with an open/close system light-shielding door at a position near an opening for inlet and outlet of a film.
Therefore, for using this type of film cartridge, a camera needs to be provided with a mechanism for opening/closing this light-shielding door at the time of mounting or dismounting this film cartridge into or from the camera, as disclosed, for example, in Jpn. Pat. Appln. KOKAI Publication No. 7-253616 or the like.
This light-shielding door is provided movably between a closing position covering a film inlet and outlet opening for shielding an external light directed toward the inside of a film cartridge main body and an opening position for making it possible to feed out or wind back a film at a position sheltered from the film inlet and outlet opening.
However, in order to prevent a film from being exposed to a light by a careless opening of the light-shielding door while the film cartridge is being carried, the cartridge of this type needs to be equipped with a light-shielding door locking member for securely locking the light-shielding door at the closed position by restricting the move of the light-shielding door.
A film cartridge actually commercialized in the market uses a locking mechanism utilizing an elastic member as a mechanism of this locking member.
In a general camera or the like using this type of film cartridge, when the film cartridge is mounted in a cartridge chamber, a light-shielding door driving member provided in the cartridge chamber becomes engaged with a light-shielding door driving groove to make the light-shielding door locking member elastically deformed to cancel a locking state, and thereafter turns the light-shielding door to open it.
Then, when the light-shielding door is in completely opened state, the force for elastically deforming the locking member is removed.
Further, when a film winding has been completed and a film take-out operation is carried out to open a cartridge chamber lid, the light-shielding door is returned to a closed state before the cartridge chamber lid is opened.
Cameras recently available in the market are fully automated progressively. For example, as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 7-306465 and others, not only a film feeding operation and a focus adjustment operation, but also an opening/closing operation of a film cartridge chamber lid and an opening/closing operation of a light-shielding door have come to be electrically driven by plunger or by motor.
According to these cameras, however, there are considered many cases where the power levels of power source batteries are lowered in the course of electrically driving various kinds of camera mechanisms so that it becomes impossible to operate the cameras themselves.
Therefore, in order to prevent a camera from being placed in such a situation in advance, a power source voltage level of a battery operation is checked prior to the starting of the operation. Based on a result of a detection of the check, a decision is made as to whether it is possible or not to operate the camera thereafter. When a decision has been made that it is not possible to operate the camera thereafter, the subsequent operation of the camera is prohibited.
However, the above camera operation control involves other problems.
These problems will be explained with reference to FIGS. 7A, 7B and 7C.
FIG. 7A is a view for illustrating a film cartridge with its light-shielding door in a closed state.
FIG. 7B is a view for illustrating the film cartridge with its light-shielding door in an opened state.
FIG. 7C is a partially enlarged view of FIG. 7B to show a state that a light-shielding door locking member is kept elastically deformed.
There will now be considered a case where pictures have been taken into all the film frames of a film in a camera using the above-described film feed-out type film cartridge, and after a film wind-back has been completed, a cartridge chamber lid opening button not shown is operated in an attempt to take out the film cartridge from the camera.
As shown in FIGS. 7A and 7B, a light-shielding door 3 is provided near an opening at a side surface 2 of a film cartridge 1.
In the normal operation, at first, an actuator not shown for electrically driving the light-shielding door 3 operates according to the operation of the cartridge chamber lid opening button, thereby to make a light-shielding door driving member 6 engaged with an engaging member 4 turn to a predetermined direction.
Then, the light-shielding door 3 is set in a closed state as shown in FIG. 7A.
Subsequently, an actuator not shown for opening/closing the cartridge chamber lid is operated so that the cartridge chamber lid is set to an opened state.
Further, for setting the light-shielding door 3 to an opened state, as shown in FIG. 7B, the actuator not shown for electrically driving the light-shielding door 3 operates to make the light-shielding door 3 turn through the light-shielding door driving member 6 and the engaging member 4, thereby to set the light-shielding door 3 to the opened state.
As explained above, in the normal operation, when the film is mounted, the light-shielding door 3 is driven to an opened state, and then a film automatic loading operation is executed.
In the camera of this type, a battery check operation is carried out when a new film cartridge has been mounted into the camera, in order to prevent the camera from being put in an inoperable situation during the film automatic loading operation.
As a result of this battery check operation, when a decision has been made that a battery voltage level is not sufficient for the automatic loading, the operation of a change from a closing to an opening of the light-shielding door and the automatic loading operation are prohibited.
In general, the open operation of the cartridge chamber lid requires a larger driving force than the close operation of the light-shielding door 3.
Accordingly, a current to be supplied to the actuator for opening the cartridge chamber lid is much larger than a current to be supplied to the actuator for closing the cartridge chamber lid.
Therefore, when the capacity of the power source battery is lowered, there could arise a situation that it is not possible to open the cartridge chamber lid although it is possible to close the light-shielding door 3.
In this situation, the light-shielding door locking member 5 is kept in an elastically deformed state, as shown in FIG. 7C.
Therefore, when this state is left as it is, a creep phenomenon occurs so that this light-shielding door locking member 5 is plastically deformed, which may result in a risk of it becoming difficult to execute a subsequent locking sufficiently.
Furthermore, there arises a similar problem to the above when some failure has occurred in the opening mechanism of the cartridge chamber lid, for example, when there arises a situation that it is not possible to open the cartridge chamber lid despite an attempt to make it in the opened state.
It is an object of the present invention to provide a camera which can avoid a plastic deformation of a light-shielding door locking member followed by a subsequent insufficient locking operation, when the capacity of a power source battery has been reduced to a lower level or when some failure has occurred in the opening mechanism of a cartridge chamber lid.
In order to achieve the above object of the invention, according to one aspect of the invention, for example, there is provided a camera adapted to use a film cartridge having a light-shielding door for opening/closing a film inlet and outlet opening, wherein the camera comprises: a cartridge chamber for accommodating the film cartridge; a cartridge chamber lid disposed at an opening of the cartridge chamber; a first driving mechanism for driving the cartridge chamber lid; a second driving mechanism for driving the light-shielding door; and control means for controlling the second driving mechanism to maintain the light-shielding door in an opened state when it is not possible to take out the film cartridge from the cartridge chamber.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.